Paper-shifting mechanism



Sept. 17,1968 F. H. SHEPARD, JR 3,

PAPER-SHIFTING MECHANISM Filed Oct. 11, 1965 2 Sheets-Sheet 1 Sept. 17, 1968 F. H. SHEPARD, JR

PAPER-SHIFTING MECHANISM 2 Sheets-Sheet 2 Filed Oct. 11, 1965 0/22 650/ pu/Jer United States Patent 3,401,782 PAPER-SHIFTING MECHANISM Francis H. Shepard, Jr., Berkeley Heights, N.J., assignor to Shepard Laboratories, Inc., Summit, NJ. Filed Oct. 11, 1965, Ser. No. 494,840 Claims. (Cl. 197-133) ABSTRACT OF THE DISCLOSURE Paper-shifting mechanism in which a lightweight pivoted arm which forms one pole of an electromagnet has a right-angle extension or shoulder at its outer end beneath which is positioned a thin flat leaf spring. The upper end of the leaf spring and the underside of the extension comprise a pair of grippers by which a strip or sheet of paper, for example, is advanced in one direction. In operation the force of inertia when the arm is suddenly moved forward causes the spring to pinch against the extension and, conversely, when the arm is suddenly retracted by the electromagnet, inertia causes the spring to move away from the extension. A further feature is in the provision for allowing the arm, when it moves forward, to bounce against a stop and as it bounces back to cock it against the electromagnet. This prevents spurious bouncing and provides for very high speed operation, for example, about 100 strokes per second.

The present invention relates to a mechanism having particular application for advancing or shifting from one line to the next the paper in a high speed printer.

At the present time, paper is advanced in a high speed printer by means of pinch rollers. In such an arrangement, the paper is grasped between an idler roller positioned on one side of the paper and a driver capstan positioned on the other side. After the paper has been moved the required distance, the driving engagement is broken by moving the idler roller out of contact from the paper.

Generally, presently available paper shift mechanisms have maximum speeds which are lower than desirable and which limit the speed of the printer. Besides being limited in speed, these mechanisms are relatively complex, which makes them costly and subject to repeated breakdowns. Furthermore, in conventional arrangements because of slippage of the paper between the idler and the capstan, these components are subject to wear.

Another disadvantage of a pinch roller type of mechanism is the problem of varying the amount of paper advance. Generally, either the time over which the idler and capstan are in contact with the paper must be varied or idlers and capstans of different diameters must be employed. Both of these approaches add complexity to the mechanism, while the latter approach can be undesirably time consuming.

Accordingly, it is an object of the present invention to provide a new and improved paper shift mechanism.

It is another object of the present invention to provide such a mechanism capable of operating at speeds consi-derably higher than the speeds of previously available mechanisms.

It is a further object of the present invention to provide a paper shift mechanism which is reliable, yet simple and inexpensive.

These and other objects will in part be understood from and in part pointed out in the following description.

In accordance with the invention, in one specific embodiment thereof, there is provided a very simple paper shifting mechanism which includes an upright arm. This arm is pivoted at its lower end and its upper end is a right-angle extension which has a flat, horizontal under- 3,401,782 Patented Sept. 17, 1968 "ice side adapted to slide upon the top of a piece or strip of paper along one edge. This arm is movable backward, in very rapid sequence, against a stop by means of an electromagnetic coil. When the coil is de-energized, the arm is swung forward, again rapidly, by a strong tension spring against another stop.

Fixed to the arm about an inch below its upper, horizontal extension is a limber leaf spring compressionally stiff because of its straightness. This extends upward but at a slight forward, wedging angle relative to the vertical axis of the arm, with the top of the spring forming a polished or rounded edge parallel to and closely opposite the underside of the right angle arm extension. This edge and the arm extension, as will be explained, automatically pinch or grip the paper when the arm suddenly swings forward and hence cause the paper to be advanced by the amount the arm swings forward.

Now when the arm is suddenly drawn back by the electromagnet, the top edge of the leaf spring, under its own inertia, and because of friction with the paper, lags the motion of the arm and hence moves relatively forward and down away from the underside of the arm extension and the paper. This permits the mechanism to cock for a subsequent advance stroke without rubbing against the paper.

When the arm is released, it is rapidly drawn forward by its tension spring. The upper end of the leaf spring, lagging the motion of the arm because of inertia and because of friction against the paper, moves relatively back and up against the arm extension thereby tightly gripping or wedging against the paper and causing it to be pulled forward by the arm for the amount of its stroke. This sequence of booking and release can be repeated at very high speed to shift paper one line at a time at a very rapid rate.

A better understanding of the invention together with a fuller appreciation of its many advantages will best be gained from the following description given in connection with the accompanying drawings wherein:

FIGURE 1 is a front elevation view of a paper shift mechanism constructed in accordance with the present invention showing the mechanism in its cocked condition;

FIGURE 2 is a side elevation view of the mechanism of FIGURE 1;

FIGURE 3 shows the mechanism of FIGURES 1 and 2 after the paper has been advanced and released;

FIGURE 4 is an enlarged perspective view of a portion of the mechanism shown in FIGURES 1, 2 and 3;

FIGURES 5, 6 and 7 illustrate the sequence of a strip of paper being gripped, advanced and released by the mechanism of FIGURES l, 2 and 3; and

FIGURE 8 shows the schematic of a circuit for energizing the mechanism.

As seen in FIGURES 1 through 3, inclusive, the paper shifting mechanism (shown substantially to scale) includes a generally vertical operating arm 10 which swings about a pivot point at its lower end defined by the axis of a stud 11. Stud 11 passes through the operating arm 10 and is fastened in a frame or base 12. The base 12, in turn, is secured to a high speed printer (not shown) by means of bolts 13.

The operating arm 10 has a right angle extension 14 at its upper end. The extension 14 is rigidly aflixed to the operating arm 10 and the two are preferably formed together as a unit. The underside of extension 14 serves as a first paper gripping member. A piece of paper 15 passes under the extension 14 as shown.

Also included in the mechanism shown in FIGURES 1 through 4 is means for moving the operating arm 10 in a first direction which corresponds to the direction of paper advance. In particular, a coil spring 16 secured to operating arm and anchored to the base 12 urges the operating arm to move clookwise about stud 11 from the full line position shown in FIGURE 1 to the position shown in dotted line. The position of the operating arm 10 shown in FIGURE 1 will be referred to as the cooked position, while the position shown in FIGURE 3 (a view from the opposite side) will be referred to as the released position. The operating arm 10 in the released position bears against a percussion cap 18 fitted on a stop screw 19. This screw 19 passes through a self-locking nut 20 secured to the base 12. The position of the threaded member 19 is adjustable by movement into or out of the nut 20. The amount of paper advance is determined by the position of screw 19. Once the desired position of the threaded member 19 is achieved, it is left locked in place.

The paper shifting mechanism further includes a second paper engaging member in the form of a leaf spring 21. The upper end of the latter, in rest position, is spaced from the extension 14 to permit the paper to pass freely between the bottom surface of extension 14 and the top edge of the leaf spring. The top edge of the leaf spring 21 serves, during dynamic movement of arm 10, to pinch the paper against the underside of extension 14. The lower end of the leaf spring 21 is secured by means of a pair of screws 23 to a member 22 extending outward at a right angle from the operating arm 10. Member 22 is rigidly fixed to arm 10 by a screw 24. The leaf spring 21 is so mounted that the top edge of the leaf spring is positioned in the path of motion of the extension 14 as it and the operating arm 10 are urged to move from the cocked position shown in FIGURE 1 toward the released position shown in FIGURE 3.

This mechanism additionally includes means for driving the operating arm 10 from the released position to the cocked position. To this end there is mounted near the lower pivoted end of arm 10 a solenoid 26 secured to the base 12 by means of bolts 27. Carried on the lower part of arm 10 and opposite solenoid 26, is an armature 28 of magnetic material which may be integral with arm 10. As the solenoid coils 26a are energized, the operating arm 10 is drawn about pivot stud 11 toward the solenoid core 26b against the action of the coil spring 16 and assumes the cocked position shown in FIGURE 1 in which armature 28 is held against core 26b by magnetic attraction. The operating arm 10 is held in the cocked position by solenoid 26 until it is desired to move the paper, after which coil 26a is de-energized and the operating arm flies rapidly from the cocked position to the released position under the urging of tension spring 16.

The springiness of leaf spring 21 is chosen so that the top edge of the leaf spring, under its own inertia lags an initial s-udden movement of the operating arm 10 and extension 14. The desired springiness, and the initial setting of spring 21, is achieved by the selection of suitable material, thickness and width for the leaf spring 21, and by the setting of a screw 25. Spring 21 is shaped and dimensioned substantially as shown in FIGURES 1-3.

FIGURE 6 illustrates the flexure of the leaf spring 21 as compared to its unflexed condition shown in FIG- URE 5. The flexure of leaf spring 21 is due to the lower end of the leaf spring moving with the operating arm 10. The arrow leading from the operating arm 10 in FIGURE 6 indicates that the operating arm is moving at this point in the cycle of operation of the mechanism. With the top edge of the leaf spring 21 remaining in the path of movement of the extension 14, the leaf spring bears against the paper 15 wedging it against the bottom surface of extension 14. The result is that the paper 15 is gripped and it and arm 10 move together counterclockwise toward the released position of FIGURE 7 to advance the paper one step. It should be noted that the angle of the spring against the pinch surface is such that the paper is jammed in one direction and will not slip when the arm pulls forward.

When the operating arm 10 reaches the released position, it hits cap 18 thereby abruptly halting. The leaf spring 21, due to its inertia, continues to move in the same direction as indicated by the arrow leading from the leaf spring in FIGURE 7 so that the paper is released. To prevent the leaf spring from undergoing unwanted oscillations its resonance frequency is preferably set well above the operating frequency of the operating arm 10. In order to avoid undesired vibrations upon impact with the percussion cap 18, the percussion cap is made of nylon and is positioned at the center of percussion of the operating arm 10.

Immediately after the leaf spring has been released, the operating arm 10 is drawn back to the cocked position by the energization of the solenoid 26. In this position the arm bears against a second stop 30 which is adjusted so that there is zero air gap between solenoid core 26b and armature 28 of arm 10. Arm 10 is guided laterally by a pair of parallel nylon bars 32 fixed to frame 12 and lying parallel to the plane of FIGURE 1.

By re-energizing solenoid 26 immediately after arm 10 hits stop 18, the normal bounce back of the arm adds to the pull of the solenoid and helps recock the arm. The solenoid is held on with reduced current after the arm is cocked and is again momentarily de-energized to advance the paper once more. This mode of operation eliminates unwanted bouncing of arm 10 against stop 18 and prevents the paper from being spuriously advanced.

The circuit for energizing solenoid 26 is shown in FIG- URE 8. This circuit applies a low hold voltage (and low current) to the solenoid to hold it cocked. The circuit momentarily drops the hold voltage to release the solenoid, and a short time later, in accordance with the time it takes arm 10 to swing against stop 18 (about 5 milliseconds in this embodiment) a large voltage (and high current) is applied to solenoid 26 to re-cock the arm, after which the voltage is dropped to its hold value (shown here as +12 v.)

The circuit of FIGURE 8 has an input 50 which receives a trigger pulse when paper is to be shifted one line. The input signal actuates a first pulser 52 whose output is applied to a first amplifier 54 and a second pulser 56. P-ulser 52 produces an approximately 8 millisecond pulse. At the end of this pulse, pulser 56 in turn produces an approximately 5 millisecond pulse which is applied to a second amplifier 58. The output voltages of amplifiers 54 and 58 are connected to coils 26a of the solenoids as shown. The voltage waveforms at the points indicated are as shown. The net result is that solenoid 26 is deenergized for about 8 milliseconds, then fully energized for the next 5 milliseconds, and then energized with reduced hold voltage until the next trigger input. The actual elements in the pulsers and amplifiers can be any of those well-known in the art.

While there has been described what is at present considered to be the preferred embodiment of this invention it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

I claim:

1. A drive arrangement of the character described comprising: a pinch feed mechanism including an arm which is pivoted at one end, the other end of which is movable back and forth at high speed over a limited arc of travel, said arm at its other end having a pair of gripping members, one of said members being movable relative to the other by inertia to pinch a strip of paper and the like when said arm is moved forward and to unpinch when said arm is moved back, said arm having a magnetic armature adjacent its pivoted end, a stationary electromagnet positioned opposite said armature to pull said arm back and hold it in a cocked position, a drive spring to move said arm forward away from said electromagnet at high speed, stop means to limit the forward travel of said arm to a desired amount, and circuit means to energize said electromagnet to hold said arm in cocked position, and to release it to move forward and to recock it at high speed, said circuit means energizing said electromagnet with a momentary release pulse and quickly thereafter with a re-cocking pulse, said release pulse lowering the holding force of said electromagnet to less than the force of said drive spring,- said re-cocking pulse being timed to energize said electromagnet to pull said arm backward to cocked position as soon as it hits said stop means and bounces back therefrom.

2. A high speed pinch feed arrangement comprising a lightweight arm supported near its bottom for pivoting back and forth, said arm comprising an armature of an electromagnet, the upper end of said arm having a right angle extension, a thin elongated flat leaf spring rigidly attached at its lower end to said arm a short distance beneath said extension and being generally aligned with the vertical axis of said arm, the upper end of said leaf spring and said extension forming a pair of grippers for advancing a strip of paper and the like, an electromagnet positioned opposite said arm and serving to pull it quickly back and hold it in cocked position against said electromagnet, spring means to pull said arm at high speed forward away from said electromagnet, stop means to suddenly stop the forward motion of said arm, said leaf spring by its inertia and in conjunction with said extension gripping the paper as the arm is rapidly driven forward and ungripping the paper as th arm is driven back, and circuit means to energize said electromagnet to hold said arm against the electromagnet in cocked position and to release the arm to move forward and then to re-cock it at high speed, said circuit means for each cycle of operation energizing said electromagnet with a momentary release pulse and quickly thereafter with a recocking pulse, said re-cocking pulse being applied as soon as said arm hits said stop means and bounces back therefrom, whereby high speed operation is obtained and spurious bouncing of said arm avoided.

3. A high speed pinch feed mechanism comprising a long thin arm supported near its bottom end for pivoting back and forth, said arm near its pivoted end having a magnetic portion which serves as the armature of an electromagnet, the other end of said arm having a right angle extension, a thin light elongated leaf spring having a generally flat surface and being rigidly attached at its lower end to said arm a short distance beneath said extension, said leaf spring having its flat surface generally at right angles to the back and forth movement of said arm, the length axis of said leaf spring being generally aligned but at a slight upward and forward angle to the length axis of said arm, the upper end of said leaf spring and the underside of said extension forming a pair of grippers for advancing a strip of paper and the like, said leaf spring by its inertia being bendable slightly at its upper end back toward said extension to pinch said paper against said extension as said arm is rapidly driven forward and bendable forward to unpinch the paper as the arm is rapidly driven backward, a stationary electromagnet positioned opposite the magnetic portion of said arm and serving to pull the arm quickly back and hold it in cocked position against said electromagnet, spring means to swing said arm rapidly forward away from said electromagnet, and stop means to limit the forward travel of said arm, said spring means urging said arm toward said stop means.

4. The mechanism in claim 3 wherein said stop means comprises a plastic bumper positioned approximately opposite the center of percussion of said arm.

5. The mechanism in claim 3 wherein said leaf spring is mounted on a block fastened to said arm, said block carrying a set screw engaging the fiat surface of said leaf spring and by which the upper end of said leaf spring can be adjusted relative to said extension of said arm.

References Cited UNITED STATES PATENTS 1,278,472 9/1918 Ireland 197133 1,278,473 9/1918 Ireland 197-133 1,682,333 8/1928 Hart 197-153 3,176,819 4/1965 Bloom et a1 l97133 ROBERT E. PULFREY, Primary Examiner.

E. T. WRIGHT, Assistant Examiner. 

